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Promoting Your Research Activities: Journal Impact

This guide will help you find tools to measure the impact of a researcher and the impact of publications, resources to create your profile and information on alternative impact measures.

Impact Factor

The impact factor is a measure of the importance or the rank of a journal. It is calculated by dividing the number of citations to the journal in a given year by the number of articles published in the journal in the previous two years.

Example:

Citations received in 2016 for all articles published in 2014 and 2015: 120
Number of articles published in 2014 and 2015: 50
Impact factor: 120/50 = 2.4

Thus, the articles published in this journal in 2014 and 2015 were cited in 2016, on average, 2.4 times.

It is generally true that journals with a high impact factor have greater visibility. Analyzing this impact factor can help authors decide in which journal to publish (although this should not be their only criterion). This measure was initially developed to help librarians choose which journals to subscribe to and not to determine the value of the contents published in these journals.

Some limitations of the impact factor:

  • The articles published in a journal with a high impact factor are not all highly cited; some articles might never be cited. (Remember, this is an average.)
  • The impact factor should not be used to assess the value of a specific article.
  • The impact factor varies enormously from one field to the other and should not be used to compare journals in different fields.
  • The impact factor can be manipulated, in particular by asking authors to cite articles from the journal in which they wish to publish.

The article The Use and Misuse of Journal Metrics presents the good and bad uses of the impact factor.

Journal Citation Reports (JCR)

To date, the Journal Citation Reports (JCR), developed by Thomson Reuters, is the only resource for finding the impact factor of over 8,000 scientific journals. The scientific journals listed in JCR are those indexed by Web of Science.

Impact factors for a given year are usually published in the summer of the following year. For example, the 2017 impact factors will be available in the summer of 2018.

It is important to know there is a North American bias in the selection of journals by Web of Science, which covers mostly English-language journals. A journal that is not indexed in this database and, therefore, does not have an impact factor, is not necessarily a poor journal.

JCR also provides other information on journals, such as their impact factor over five years, the total number of citations, the Eigenfactor score, etc.

You can search by journal title or by subject. For more information, consult this tutorial.

Eigenfactor

The Eigenfactor score ranks the importance of a journal by assessing its entire network of citations. This indicator is calculated using an algorithm similar to the one used by Google.

The Eigenfactor:

  • Does not take into account the self-citations;
  • Takes into consideration the data from the last five years (compared to two years for the impact factor);
  • Is adjusted according to the citation differences across various disciplines;
  • Considers the source of citations;
  • Is available for over 11,000 journals until 2014. For more recent years, see the Journal Citation Reports, which provides the Eigenfactor starting 2007.

Eigenfactor.org also presents citation networks, that let you create interactive maps, as well as information on the method used to calculate it.

SCIMAGO journal and country rank

The SCImago Journal and Country Rank (SJR) provides an indicator showing the visibility of the journals indexed in the Scopus database. This indicator was developed by SCImago based on the algorithm Google PageRank. SJR also provides bibliometric data (number of citations, self-citations, citations per document, and h-index) for more than 230 countries.

You can search by the exact title of a journal or by subject.

Access to SJR is free, even without a Scopus subscription.

Beware of False Indicators

Some journals put forward indicators such as the "International Impact Factor" or the "Journal Quality Factor". On the websites of these indicators, you will often notice spelling mistakes, a vague or even plagiarized assessment method, as well as a lack of contact information.

Beware of journals using such indicators and check their credibility (peer review, other articles already published in this journal, other indicators, etc.) before publishing your work there.

Usefulness of Impact Factors

David Pendlebury, from Thomson Reuters, presents the impact factor.

Some rankings

Journal Impact Factor (2015) Eigenfactor (2015) SCIMAGO journal rank (2015)
Nature 38.1 1.45 21.9
Applied Physics Letters 3.1 0.38 1.1
Optics Express 3.1 0.23 2.2
Journal of Biomechanics 2.4 0.03 1.2
Polymer Engineering and Science 1.7 0.01 0.6

Journal Citation Reports

A tutorial created by Thomson Reuters on using Journal Citation Reports.

DORA

The San Francisco Declaration on Research Assessment, DORA was written by a group of researchers and scholarly journals publishers in 2012.

DORA puts forward several recommendations to improve the way in which research quality is evaluated, in particular by eliminating the use of journal-based indicators, like the impact factor, to evaluate individual researchers.

Logo DORA

For more information

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